Sheikh Abdul Azeez bin Abdur-Razzaaq Al-Ghudayaan - a judge at the General court in al-Khobar, Saudi Arabia, mentioned,
A resolution issued by the Commission of Senior Scholars in the 56th session under No. 207 dated 9.11.1422 AH. states that the saa' used at the Prophet's time is equal to three litres and thirty millilitres.
This is extremely close to what Shaykh Yahya Mudarris al-Hindi thumma Makki has mentioned. Please refer here.
Sheikh Abdul Azeez al-Ghudayaan comments regarding such trivial differences as follows, "According to the juristic rules, any trivial difference is neglected for this estimation is not certain with regard to the Prophet's saa'; it is a discretionary estimation and may be closer to the right estimation, and Allah knows best. Had it been obligatory to now the specific amount of the saa' and had it been forbidden to use a discretionary amount, our predecessors would have given specific amounts of these measuring units and such amounts would have reached us through unanimous narrations."